Garza, who was retroactively placed on the 15-day DL on May 18 with a right elbow contusion, will throw a bullpen session on Wednesday, and if all goes well he will throw another on Saturday in St. Louis.
The Cubs were hoping Garza, who is eligible to come off the DL on Friday, would be able to pitch against the Cardinals this weekend.
Garza reported no pain after throwing from flat ground before Monday's game against the Houston Astros at Wrigley Field.
"Everything felt great," Garza said Monday. "Obviously [I] won't be able to test [my arm] 100 percent until game time, but right now I feel great."
Garza, who has not thrown since May 17 in Cincinnati when he went six innings in a no-decision, has a 3.72 ERA and leads the National League with 10.99 strikeouts per nine innings. He is the third member of the Cubs' starting rotation to hit the disabled list this season.
Bruce Levine covers the Cubs for ESPNChicago.com and ESPN 1000.